RE: [PATCH v2] drm/ast: Disable fast reset after DRAM initial

[Kuo-Hsiang Chou <kuohsiang_chou@aspeedtech.com>]

-----Original Message-----
From: Thomas Zimmermann [mailto:tzimmermann@suse.de] 
Sent: Monday, January 18, 2021 5:06 PM
To: Kuo-Hsiang Chou <kuohsiang_chou@aspeedtech.com>; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org

Subject: Re: [PATCH v2] drm/ast: Disable fast reset after DRAM initial

Hi, Thomas,

Hi

Am 12.01.21 um 08:58 schrieb KuoHsiang Chou:
> [Bug][AST2500]
> 
> V1:
> When AST2500 acts as stand-alone VGA so that DRAM and DVO 
> initialization have to be achieved by VGA driver with P2A (PCI to AHB) enabling.
> However, HW suggests disable Fast reset mode after DRAM initializaton, 
> because fast reset mode is mainly designed for ARM ICE debugger.
> Once Fast reset is checked as enabling, WDT (Watch Dog Timer) should 
> be first enabled to avoid system deadlock before disable fast reset mode.
> 
> V2:
> Use to_pci_dev() to get revision of PCI configuration.
> 
> Signed-off-by: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
> ---
>   drivers/gpu/drm/ast/ast_drv.h  |  1 +
>   drivers/gpu/drm/ast/ast_main.c |  5 +++
>   drivers/gpu/drm/ast/ast_post.c | 71 +++++++++++++++++++++-------------
>   3 files changed, 51 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_drv.h 
> b/drivers/gpu/drm/ast/ast_drv.h index da6dfb677540..a2cf5fef2399 
> 100644
> --- a/drivers/gpu/drm/ast/ast_drv.h
> +++ b/drivers/gpu/drm/ast/ast_drv.h
> @@ -320,6 +320,7 @@ bool ast_is_vga_enabled(struct drm_device *dev);
>   void ast_post_gpu(struct drm_device *dev);
>   u32 ast_mindwm(struct ast_private *ast, u32 r);
>   void ast_moutdwm(struct ast_private *ast, u32 r, u32 v);
> +void ast_patch_ahb_2500(struct ast_private *ast);
>   /* ast dp501 */
>   void ast_set_dp501_video_output(struct drm_device *dev, u8 mode);
>   bool ast_backup_fw(struct drm_device *dev, u8 *addr, u32 size); diff 
> --git a/drivers/gpu/drm/ast/ast_main.c 
> b/drivers/gpu/drm/ast/ast_main.c index 3775fe26f792..0e4dfcc25623 
> 100644
> --- a/drivers/gpu/drm/ast/ast_main.c
> +++ b/drivers/gpu/drm/ast/ast_main.c
> @@ -69,6 +69,7 @@ static void ast_detect_config_mode(struct drm_device *dev, u32 *scu_rev)
>   {
>   	struct device_node *np = dev->pdev->dev.of_node;
>   	struct ast_private *ast = to_ast_private(dev);
> +	struct pci_dev *pdev = to_pci_dev(dev->dev);
>   	uint32_t data, jregd0, jregd1;
> 
>   	/* Defaults */
> @@ -96,6 +97,10 @@ static void ast_detect_config_mode(struct drm_device *dev, u32 *scu_rev)
>   	jregd0 = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xd0, 0xff);
>   	jregd1 = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xd1, 0xff);
>   	if (!(jregd0 & 0x80) || !(jregd1 & 0x10)) {
> +		/* Patch AST2500 */
> +		if (((pdev->revision & 0xF0) == 0x40) && ((jregd0 & 0xC0) == 0))
> +			ast_patch_ahb_2500(ast);
> +
>   		/* Double check it's actually working */
>   		data = ast_read32(ast, 0xf004);
>   		if (data != 0xFFFFFFFF) {
> diff --git a/drivers/gpu/drm/ast/ast_post.c 
> b/drivers/gpu/drm/ast/ast_post.c index 8902c2f84bf9..1f0007daa005 
> 100644
> --- a/drivers/gpu/drm/ast/ast_post.c
> +++ b/drivers/gpu/drm/ast/ast_post.c
> @@ -2026,6 +2026,33 @@ static bool ast_dram_init_2500(struct ast_private *ast)
>   	return true;
>   }
> 
> +void ast_patch_ahb_2500(struct ast_private *ast) {
> +	u32	data;
> +
> +patch_ahb_lock:
> +	/* Clear bus lock condition */
> +	ast_moutdwm(ast, 0x1e600000, 0xAEED1A03);
> +	ast_moutdwm(ast, 0x1e600084, 0x00010000);
> +	ast_moutdwm(ast, 0x1e600088, 0x00000000);
> +	ast_moutdwm(ast, 0x1e6e2000, 0x1688A8A8);
> +	data = ast_mindwm(ast, 0x1e6e2070);
> +	if (data & 0x08000000) {					/* check fast reset */
> +
> +		ast_moutdwm(ast, 0x1E785004, 0x00000010);
> +		ast_moutdwm(ast, 0x1E785008, 0x00004755);
> +		ast_moutdwm(ast, 0x1E78500c, 0x00000033);
> +		udelay(1000);
> +	}
> +	ast_moutdwm(ast, 0x1e6e2000, 0x1688A8A8);
> +	do {
> +		data = ast_mindwm(ast, 0x1e6e2000);
> +		if (data == 0xffffffff)
> +			goto patch_ahb_lock;
> +	}	while (data != 1);
> +	ast_moutdwm(ast, 0x1e6e207c, 0x08000000);	/* clear fast reset */
> +}
> +
>   void ast_post_chip_2500(struct drm_device *dev)
>   {
>   	struct ast_private *ast = to_ast_private(dev); @@ -2033,39 +2060,31 
> @@ void ast_post_chip_2500(struct drm_device *dev)
>   	u8 reg;
> 
>   	reg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xd0, 0xff);
> -	if ((reg & 0x80) == 0) {/* vga only */
> +	if ((reg & 0xC0) == 0) {/* vga only */
>   		/* Clear bus lock condition */
> -		ast_moutdwm(ast, 0x1e600000, 0xAEED1A03);
> -		ast_moutdwm(ast, 0x1e600084, 0x00010000);
> -		ast_moutdwm(ast, 0x1e600088, 0x00000000);
> -		ast_moutdwm(ast, 0x1e6e2000, 0x1688A8A8);
> -		ast_write32(ast, 0xf004, 0x1e6e0000);
> -		ast_write32(ast, 0xf000, 0x1);
> -		ast_write32(ast, 0x12000, 0x1688a8a8);
> -		while (ast_read32(ast, 0x12000) != 0x1)
> -			;
> -
> -		ast_write32(ast, 0x10000, 0xfc600309);
> -		while (ast_read32(ast, 0x10000) != 0x1)
> -			;
> +		ast_patch_ahb_2500(ast);
> +
> +		/* Disable watchdog */
> +		ast_moutdwm(ast, 0x1E78502C, 0x00000000);
> +		ast_moutdwm(ast, 0x1E78504C, 0x00000000);
> +		/* Reset USB port */
> +		ast_moutdwm(ast, 0x1E6E2090, 0x20000000);
> +		ast_moutdwm(ast, 0x1E6E2094, 0x00004000);
> +		if (ast_mindwm(ast, 0x1E6E2070) & 0x00800000) {
> +			ast_moutdwm(ast, 0x1E6E207C, 0x00800000);
> +			mdelay(100);
> +			ast_moutdwm(ast, 0x1E6E2070, 0x00800000);
> +		}
> +		/* Modify eSPI reset pin */
> +		temp = ast_mindwm(ast, 0x1E6E2070);
> +		if (temp & 0x02000000)
> +			ast_moutdwm(ast, 0x1E6E207C, 0x00004000);

Instead of answering my question, you simply deleted the comments. It doesn't work like that.

My bad!
About to /* add at V1.2 */ and /* add at V1.3 */, the comments should be some marks of recommendations came from HW designer.
Therefore, I thought this kind of comments could be deleted directly.
Sorry for my poor English, so that the biggest error is that I misunderstood your question likes a sentence of "why not ....".
Should I recover the comments? Thanks!

Best Regards,
	Kuo-Hsiang Chou


Best regards
Thomas

> 
>   		/* Slow down CPU/AHB CLK in VGA only mode */
>   		temp = ast_read32(ast, 0x12008);
>   		temp |= 0x73;
>   		ast_write32(ast, 0x12008, temp);
> 
> -		/* Reset USB port to patch USB unknown device issue */
> -		ast_moutdwm(ast, 0x1e6e2090, 0x20000000);
> -		temp  = ast_mindwm(ast, 0x1e6e2094);
> -		temp |= 0x00004000;
> -		ast_moutdwm(ast, 0x1e6e2094, temp);
> -		temp  = ast_mindwm(ast, 0x1e6e2070);
> -		if (temp & 0x00800000) {
> -			ast_moutdwm(ast, 0x1e6e207c, 0x00800000);
> -			mdelay(100);
> -			ast_moutdwm(ast, 0x1e6e2070, 0x00800000);
> -		}
> -
>   		if (!ast_dram_init_2500(ast))
>   			drm_err(dev, "DRAM init failed !\n");
> 
> --
> 2.18.4
> 
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> 

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer